//  BestSolutionSelection.java
//
//  Author:
//       Antonio J. Nebro <antonio@lcc.uma.es>
//       Juan J. Durillo <durillo@lcc.uma.es>
//
//  Copyright (c) 2011 Antonio J. Nebro, Juan J. Durillo
//
//  This program is free software: you can redistribute it and/or modify
//  it under the terms of the GNU Lesser General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU Lesser General Public License for more details.
// 
//  You should have received a copy of the GNU Lesser General Public License
//  along with this program.  If not, see <http://www.gnu.org/licenses/>.

package etmo.operators.selection;

import java.util.Comparator;
import java.util.HashMap;

import etmo.core.SolutionSet;

/**
 * This class implements a selection operator used for selecting the best
 * solution in a SolutionSet according to a given comparator
 */
public class BestSolutionSelection extends Selection {

	// Comparator
	private Comparator comparator_;

	public BestSolutionSelection(HashMap<String, Object> parameters) {
		super(parameters);

		comparator_ = null;

		if (parameters.get("comparator") != null)
			comparator_ = (Comparator) parameters.get("comparator");
	}

	/**
	 * Constructor
	 * 
	 * @param comparator
	 */
	// public BestSolutionSelection(Comparator comparator) {
	// comparator_ = comparator ;
	// }

	/**
	 * Performs the operation
	 * 
	 * @param object
	 *            Object representing a SolutionSet.
	 * @return the best solution found
	 */
	public Object execute(Object object) {
		SolutionSet solutionSet = (SolutionSet) object;

		if (solutionSet.size() == 0) {
			return null;
		}
		int bestSolution;

		bestSolution = 0;

		for (int i = 1; i < solutionSet.size(); i++) {
			if (comparator_.compare(solutionSet.get(i), solutionSet.get(bestSolution)) < 0)
				bestSolution = i;
		} // for

		return bestSolution;
	} // Execute
} // BestObjectiveSelection
